Field of the Invention
The invention relates to a heat exchanger, particularly an evaporator, as it used particularly for a heating or air conditioning system for motor vehicles.
Description of the Background Art
Evaporators are known in which the two-phase refrigerant is distributed from an inlet channel to a flow device, preferably tubes, especially flat tubes. After flowing through the flat tubes, the vaporous refrigerant leaves the evaporator via an outlet channel.
In this regard, the uniform distribution of the liquid refrigerant along the entire length of the inlet channel causes difficulties. The reason for this, among others, is the formation of different flow forms as a function of the operational state. Furthermore, the segregation of the two-phase refrigerant mixture, which is homogeneous when entering the evaporator, along the length of the inlet channel also plays a special role. Individual tubes are therefore supplied solely with refrigerant vapors, as a result of which the evaporator performance worsens.
FIG. 1 shows a heat exchanger 1, particularly an evaporator for a motor vehicle air conditioning system according to the conventional art, and hereby particularly the flow course of the refrigerant. A heat exchanger of this type has an inlet channel 2, through which the refrigerant is supplied to the heat exchanger from a refrigerant circuit (not shown), via an inlet opening 18 (indicated by arrow A). Inlet channel 2 is formed elongated and is terminated by two ends.
Further, heat exchanger 1 has a collector 12, which includes an injection plate 5, a distribution plate 6, and a bottom plate 7. The refrigerant is supplied via this collector to a flow device 8, preferably flat tubes.
Between the tubes, heat conducting fins are arranged around which a medium, preferably air L (indicated by an arrow), can flow.
The tubes and the holes in bottom plate 7 are divided in the middle by a bar (not shown), so that two flow regions 14 and 15 are formed, through which the refrigerant flows in an opposite direction.
The refrigerant therefore flows first, following the arrow B, through a flow region 14, is then deflected through an intermediate chamber 13, which includes a bottom plate 9, a deflection plate 10, and an end plate 11, following the arrow C, and flows through a flow region 15 in the opposite direction, following the arrow D, into collector 12. Preferably, flow region 15 faces the incoming air L.
A plurality of injection holes 16 are provided in injection plate 5 of collector 12, so that the refrigerant can flow into flow region 14 from inlet channel 2 via openings (not shown), which correspond to injection holes 16. Furthermore, intake holes 17 are provided in injection plate 2, so that the refrigerant can flow in from flow region 15 into outlet channel 3. Via outlet channel 3, the refrigerant then enters a refrigerant circuit (not shown) (indicated by arrow E).
An evaporator of this type according to the invention is called an evaporator with deflection depth-wise.
FIG. 1b shows another evaporator according to the prior art. An evaporator of this type differs from the evaporator shown in FIG. 1a particularly in the conduct of the refrigerant in flow device 8. According to FIG. 1b, injection holes 16 and intake holes 17 are arranged offset in the injection plate. The refrigerant therefore flows first in the inlet channel (indicated by arrow A), is subsequently distributed via injection holes 16 to the flow device, and following arrows B and C reaches the outlet channel through the intake holes, and flows out of the evaporator following arrow D. An evaporator of this type according to the invention is called an evaporator with a deflection width-wise.
Evaporators of this type, however, leave something to be desired in regard to a uniform distribution of the liquid refrigerant to all flat tubes.